Different methods and arrangements for producing elongated beams are known to the art, these methods and arrangements having been adapted to the material from which the beam is composed.
An example of the present state of the art in this respect is found in the plant machinery illustrated and described in International Patent Application PCT/SE84/00303. This publication illustrates and describes an arrangement for producing an elongated member (a beam), in which a compression arrangement incorporated in a compression section is intended to displace and to compress separate batches of chip fibre which are moistened with binder and clearly defined by weighing, these compressed, separate material batches being intended to pass, in sequence, through a high-frequency heating section.
The subject matter of Swedish Patent Specification 415 547 (Swedish Patent Application 7809708-4) also belongs to the prior state of the art. This specification teaches a heating section arrangement in which the wall parts of said section can move reciprocatingly in a horizontal direction and function in part as means for transporting compressed, chip-fibre batches.
In each of these known embodiments, the beam is produced from separate, well defined material batches which are mutually separated by a boundary section or interface section of varying degrees of compression and also, to some extent, fibre directions which are displaced relative to one another in the vertical plane, and wherein the requisite curing of the batches is effected in a heating section.
The contents of the respective following publications also forms part of the known prior art with respect to the principles of the present invention.
It is known from publication FR-1 589 723 to use in extrusion processes a screw conveyor which has a decreasing pitch.
Publication DE-A-2 304 088 teaches a method of controlling the rotational speed of an extruder screw.
Publication GB-A 484 544 teaches a method in which there is used a starting material which comprises disintegrated cork admixed with a binder and used to produce a continuous elongated member or beam. Part of an elongated extrusion passage is displaced axially at the same speed as the material during a part of the compression movement, so as to reduce friction.
This publication teaches an application in which the material mixture is pressed by means of a plunger or piston through a passage of rectangular cross-section, where the upper and the lower wall surfaces are stationary whereas the side surfaces are movable and extend beyond the upper wall. The movable surfaces or walls are connected to the piston via clearance-defining means. This means has the form of a projection provided on the piston and coacting with a groove in the walls. The size of this clearance can be adjusted with the aid of an adjusting screw.
The material mixture is fed from a feed hopper into a compression space and is there compressed initially by the starting movement of the piston, with the side walls stationary, whereafter the compressed part of the material mixture and the two side walls are moved together during terminal movement of the piston.
When the piston is withdrawn, the side walls remain stationary until the piston carries out its terminal movement.
Similar to the invention, it is also known to use granulated waste plastic, waste paper, waste metal foil and the like for producing extruded profiled sections. Reference is made in this respect to publication SE-B-410 946, which makes reference to a polyolefin plastic proportion of 60-80% and the remainder paper or board, and optionally also up to 5% by weight metal.
Publication DE-B-1 778 230 describes the possibility of producing profiled bodies by producing a mixture of granulated waste plastic and paper, shaping the mixture, and incorporating 20% paper waste as a filling agent.
For the sake of completeness it can also mentioned that a large number of machines for compressing granulated material to briquette form are known to the art.
The International Patent Application PCT/SE89/00652 also teaches a method and apparatus for constructing a beam or elongated member from a mixture of plastic material and a filler material, such as wood fibres, textile fibres and the like, by subjecting the mixture to compression while the plastic material portion of the mixture is tacky or in a molten state.